The first X-Man, Scott Summers possesses the mutant ability to emit powerful force blasts from his eyes. He is visually distinctive for the ruby quartz visor he wears to control his devastating power. A born leader, Cyclops succeeded his mentor Professor X to command the X-Men.

Cyclops possesses the mutant ability to project a beam of heatless ruby-colored concussive force from his eyes, which act as inter-dimensional apertures between this universe and another. Cyclops' body constantly absorbs ambient energy, such as sunlight, from his environment into his body's cells that allows him to open the apertures

@VesKaGan: Nvm, re-read the post and in your quote it says his energy comes from the other dimension. The sunlight just helps the portals, just because he has no sunlight doesn't mean he would lose his ability to fire, he just wouldn't be able to shoot as powerful of a blast.

I always thought they invented the dimension-portal-stuff because they couldn't quite explain how his body could produce and store so much energy from sunlight, but he still needed the light to keep the portals open. Because during Claremonts run they were on a planet with no sunlight at all and he ran out of power, so Storm recharged him with lightning. It is also stated (I got this from the booklet that comes with the Marvel figurine, but I think it is from the Official Handbook of the Marvel Universe") that "It has been argued that Cyclops could therefore prevent himself from generating the force beams by confining himself to a place sealed off from sunlight. However, for unknown reasons, deprivation of sunlight for extended periods sets up a dangerous physiological imbalance of unknown nature in Cyclops' body."